Molecular analysis of TSK mouseas a model of scleroderma

人类进行性系统性硬皮病的小鼠模型，TSK小鼠，发展为硬皮病和肺气肿。我们已经成功地鉴定了一种突变形式的纤维蛋白1基因，它编码一种基因内复制形式。我们通过瞬时转染实验证明这种突变形式的纤维蛋白1能在COS7细胞的培养上清液中分泌。为了检测这种突变形式的纤维蛋白1是否导致硬皮病的表型，我们建立了鸡β-肌动蛋白启动子下的硬皮病转基因小鼠。随着年龄的增长，小鼠的皮肤厚度增加，羟脯氨酸含量增加，但不会出现肺气肿。他们有针对拓扑异构酶I的自身抗体，但没有针对纤维蛋白的自身抗体。此外，用含有突变的纤维蛋白1的表达载体作为DNA疫苗免疫野生型小鼠，也出现了一过性皮肤增厚，羟脯氨酸含量增加，并产生了纤维蛋白自身抗体。这种方法也没有诱发肺气肿。综上所述，我们得出的结论是，突变的纤维蛋白1基因是在TSK小鼠中观察到的部分表型的致病基因。导致肺气肿的原因有两种可能：第一，突变的纤维蛋白1的表达水平不足以满足肺气肿的表现。其次，还有另一个或多个与突变的纤维蛋白1非常接近的基因。为了测试这些可能性，另一只转基因小鼠正在角蛋白14启动子或延伸因子启动子的作用下产生。

A mouse model of human progressive systemic scleroderma, TSK mice, develop scleroderma and pulmonary emphysema. We have succeeded in identify a mutated form of fibrillin 1 gene, which encodes a intrageneic duplication form. We demonstrated that this mutated form of fibrillin 1 was secreted in culture supernatant of COS7 cells by transient transfection assay. To examine whether this mutated form of fibrillin 1 causes the phenotype of scleroderma, transgenic mice of it under chicken β-actin promoter were generated. The mice developed the thickness of skin along with increased content of hydroxyproline as they aged but not emphysema. And they had autoantibododies for topoisomerase I but not for fibrillin. In addition, wild type mice, which was immunized with expression vector containing the mutated fibrillin 1 as a DNA vaccination method, also developed transient skin thickness with increased hydroxyproline content and autoantibodies for fibrillin. This method did not induce emphysema either. Taken all together, it was concluded that the mutated fibrillin 1 is a causative gene for parts of the phenotypes observed in TSK mice. There are two possibilities for the reason why the emphysema was not caused by this mutated fibrillin 1. First, expression level of the mutated fibrillin 1 was not sufficient for the manifestation of emphysema. Second, there was another responsible gene or genes very close to the mutated fibrillin 1. To test these possibility, another transgenic mice are being generated under keratin 14 promoter or elongation factor promoter.